1. Field of the Invention
The present invention relates to an apparatus and method for performing recordation by irradiating a light beam to a recording medium.
2. Description of the Related Art
It is necessary to control an emission power of a light source (laser diode or the like) to maintain a predetermined constant value during recording operation in order to achieve a satisfactory reproduction performance with a recording and/or reproducing apparatus or an optical disc drive for use with a recordable or rewritable optical disc, such as a DVD-R (Digital Versatile Disc-Recordable), a CD-R (Compact Disc-Recordable), a DVD-RW (DVD-Rewritable), and a CD-RW (CD-Rewritable).
Conventionally, the laser diode is driven by a driving current which is servo-controlled so as to maintain light power at a constant level when reading from an optical disc. When performing recording, the driving current is added with a current necessary to achieve a light power for recording while performing the servo control. FIG. 1 shows power characteristics of the laser diode which is dependent on the temperature of the laser diode. More specifically, the drawing shows a relation of light power (L) versus driving current (Id) in terms of the temperature of the laser diode as a parameter. Light power of the laser diode increases approximately linearly with respect to a driving current when the driving current is larger than an oscillation threshold value (Ith). As the temperature of the laser diode increases, the oscillation threshold value increases while slope efficiency or external differential quantum efficiency (xcex7d[W/A]) representing a gradient of the characteristics curve decreases.
It is a problem in the above-described conventional driving method of the laser diode that recording light power varies because the external differential quantum efficiency of the laser diode varies as the temperature of the laser diode changes. It is another problem in the conventional driving method that the individual differences among laser diodes cause variations in light power during recording operation, because the temperature dependence of the laser diode characteristics varies from element to element.
Further, it is difficult to maintain the recording light power at the optimal value over time because the laser diode characteristics change with deterioration.
The present invention has been made to overcome the above-described problems, and it is an object of the present invention to provide an optical recording apparatus capable of performing a light power control for recording with high accuracy in a stable manner regardless of a change in light emission efficiency of a light source with temperature or over time and a characteristics difference among individual light sources, and a method thereof.
To achieve the object, according to one aspect of the present invention, there is provided an optical recording apparatus for performing recording by irradiating a light beam emitted from a light source to a recording medium, which comprises a light source driving portion for driving the light source to emit the light beam; an emission light power detecting portion for detecting an emission light power from the light source; and a light power adjusting portion for controlling the light source driving portion based on a detected light power by the emission light power detecting portion to adjust the emission light power from the light source.
According to another aspect of the present invention, there is provided an optical recording apparatus for performing recording by irradiating a light beam emitted from a light source to a recording medium, which comprises a light source driving portion for driving the light source to emit a first light beam and a second light beam having a light power smaller than the light power of the first light beam; an emission light power detecting portion for detecting an emission light power from the light source; and a light power adjusting portion for adjusting the emission light power of the first light beam and the emission light power of the second light beam based on a detected light power of the first light beam by the emission light power detecting portion.
According to another aspect of the present invention, there is provided an optical recording apparatus for performing recording by irradiating a light beam emitted from a light source to a recording medium, which comprises a light source driving portion for driving the light source to emit a first light beam and a second light beam having a light power smaller than a light power of the first light beam; an emission light power detecting portion for detecting emission light power from the light source; and a light power adjusting portion for adjusting the emission light power of the first light beam based on a light power detection value of the second light beam by the emission light power detecting portion.
According to another aspect of the present invention, there is provided a method of an optical recording apparatus for performing recording by irradiating a light beam emitted from a light source to a recording medium, which comprises the steps of driving the light source to emit the light beam; detecting an emission light power from the light source; and adjusting the emission light power from the light source on the basis of a detected light power in the step of detecting an emission light power.
According to another aspect of the present invention, there is provided a method of an optical recording apparatus for performing recording by irradiating a light beam emitted from a light source to a recording medium, which comprises the steps of driving the light source to emit a first light beam and a second light beam having a light power smaller than the light power of the first light beam; detecting an emission light power from the light source; and adjusting the emission light power of the first light beam and the emission light power of the second light beam based on a detected light power of the first light beam in the step of detecting an emission light power.